Black soot coming out of exhaust

R

Rachel!!!!

Member
 Suffolk
I have a 2006 2.5si on 66k

For the last 2 months roughly I've noticed black soot on the bumper above the exhaust and the tail pipes are black. It never did this before. It's not every time I drive and I think it's possibly when stuck in traffic. No other issues as far as I'm aware, no lights on dash, not using oil.

Is there something this is likely to be? Or anything I can check myself before taking it to a garage?
 
Black smoke/soot is over-fuelling car running too rich... could be a number of things, need a code reader first to see if any faults thrown up :thumbsup:
 
Running rich, with diagnostics take a look at live data from the fuel trims if they are high it could be down to a couple of reasons.
1. Air leaks in the vaccum system across the engine from post Maf to exhaust including all the CCV pipes, oil filler cap and dipstick tube O ring. Any split or holed rubbers should be replaced.
2. Faulty Maf, not registering the correct amount of air passing into the throttle body, if its over reporting the ECU will see this as a lean mixture much the same as extra air from holes or splits as in No.1. You could try cleaning the Maf with specific Maf cleaner spray, don't use anything else and don't touch the sensor with your fingers.
It is worth noting that if the electrical connection is disconnected the car will run on default settings, worth trying this to see if it makes any difference, with it disconnected take a loog at live data from the fuel trims see if they have dropped. If they have thats an indication that the Maf is at fault, Maf's dont always set fault codes EML lights tend to be triggered because something else upstream ao downstram of the Maf has detected something wrong.

Always good to do a smoke test on these engines to find any air leaks you can't find by visual checks.
 
As always, [ref]colb[/ref] has provided good advice. You may of course need to find someone with a suitable code reader.
Maybe worth mentioning where you are, to see if there is a forum 'expert' nearby who could help.

One more thing: was anything changed on the car around the same time that may have introduced this problem?
 
Nothing has been changed on the car however thinking about it at the begining of Feb when we had all that snow the car Sat for about 5 days and wouldn't start. I tried jump starting it which got there in the end after a few tries but it didn't seem like it was the battery at fault, it's also a new battery and I've had no battery issues before or after that. I wondered at the time if snow had drifted in the front grill? I'd stupidly parked it so that could happen. I have no idea if that could explain it but it did start with the soot after that, I'm not sure how long after or if that could have done anything?

I'm in Suffolk but not far from the Norfolk border near Diss. I don't have a code reader so if anyone does around this way that would be very handy otherwise it will have to go to a garage.
 
Rachel!!!! said:
Nothing has been changed on the car however thinking about it at the begining of Feb when we had all that snow the car Sat for about 5 days and wouldn't start. I tried jump starting it which got there in the end after a few tries but it didn't seem like it was the battery at fault, it's also a new battery and I've had no battery issues before or after that. I wondered at the time if snow had drifted in the front grill? I'd stupidly parked it so that could happen. I have no idea if that could explain it but it did start with the soot after that, I'm not sure how long after or if that could have done anything?

I'm in Suffolk but not far from the Norfolk border near Diss. I don't have a code reader so if anyone does around this way that would be very handy otherwise it will have to go to a garage.
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Well I'm in Attleborough so not too far from you, and do have a code reader you are welcome to borrow.
However, I am no expert, so once we got codes I would still be relying on the kind people on here to help advise.
I'll PM you my mobile if you fancy a run out this way to check it?
 
[ref]colb[/ref], can you give any pointers as to what we should be looking at regarding codes etc.
I would make a note of all the ones showing, then reset and see what comes back.
I have an Autophix5900 which seems pretty comprehensive in its functions.
Just knowing which areas to look in would help a bit.
So far only used it on wifey's 2.5i which is the M54 engine, so not sure what differences there might be.

EDIT: Also, if the front grille was full of snow, is it likely that got dragged into the intake when the engine finally started and may have caused an issue.
For example, maybe now the air filter is a soggy mess?
I'm thinking, maybe it is worth whipping the air filter out first and checking there's no debris etc in there too?
Its a simple check to eradicate that as a problem.
 
Thanks for your number, that would be great if I could come over and see what codes we get. I'll send you a text later. I will also have a look at the air filter this afternoon when I get home from work and check that.
 
Rachel!!!! said:
Thanks for your number, that would be great if I could come over and see what codes we get. I'll send you a text later. I will also have a look at the air filter this afternoon when I get home from work and check that.
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No problems. Hope I can actually help..........
 
Code read it and see what comes up, good idea to check the air filter also have a good look at all the rubber intake bellows and all vaccum hoses and plastic pipes for splits or holes that could be the cause of the rich running as it may be seeing unmetered air that has not been measured by the Maf, when it gets picked up in the exhaust it thinks its running lean so adds more fuel to compensate. If it is doing that then looking at the fuel trims to see if they are high would add to the suspicion of air leaks or bad Maf. Its worth noting that over fueling will eventually trigger the EML to indicate something is amiss, bad Maf's dont always set codes or light the EML. A smoke test is a sure fire way of finding any air leaks that can't be found visually. Clear any codes you find after all these checks have been made and give the car a run then rescan and see if any codes return.
 
colb said:
Code read it and see what comes up, good idea to check the air filter also have a good look at all the rubber intake bellows and all vaccum hoses and plastic pipes for splits or holes that could be the cause of the rich running as it may be seeing unmetered air that has not been measured by the Maf, when it gets picked up in the exhaust it thinks its running lean so adds more fuel to compensate. If it is doing that then looking at the fuel trims to see if they are high would add to the suspicion of air leaks or bad Maf. Its worth noting that over fueling will eventually trigger the EML to indicate something is amiss, bad Maf's dont always set codes or light the EML. A smoke test is a sure fire way of finding any air leaks that can't be found visually. Clear any codes you find after all these checks have been made and give the car a run then rescan and see if any codes return.
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Cheers. Look like we'll be getting together at some point to take a look. It may be a case of sending you some before and after codes if we can't find anything.
 
The air filter is definately ok, it's dry and clean.
I had a friend look at all the plastic hoses and pipes etc and he said everything looks brand new and definately doesn't look like any problems there. He queried if it could just be short journeys? At the min I'm mostly just driving 7 miles each way to work a day. Could it be that?
 
Continual short drives are not good for a car. It does not really get up to optimum temperature. I would get the car scanned as you have planned per OP. But I would also make sure to run "high test" gas in it if you have not been doing it. There are also additives you can add to your tank of gas to help clean out any sludge from the short trips. Would take it for a long spirited run after doing these things. Good luck with your issue.
 
Rachel!!!! said:
The air filter is definately ok, it's dry and clean.
I had a friend look at all the plastic hoses and pipes etc and he said everything looks brand new and definately doesn't look like any problems there. He queried if it could just be short journeys? At the min I'm mostly just driving 7 miles each way to work a day. Could it be that?
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Possibly, if it never gets a long run?
But hey, a blast up the road from Diss to Attleborough should help that, and you'd go home with lots of new worries about codes you never knew you had. :poke: :D
We're considering a run to Southwold over the weekend. Don't suppose you'd fancy meet up there?
 
rdm05z4 said:
Continual short drives are not good for a car. It does not really get up to optimum temperature. I would get the car scanned as you have planned per OP. But I would also make sure to run "high test" gas in it if you have not been doing it. There are also additives you can add to your tank of gas to help clean out any sludge from the short trips. Would take it for a long spirited run after doing these things. Good luck with your issue.
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I've always used Shell or BP fuel and on the last 2 fill ups I've gone for the Shell V Power so I will stick with that, I also put in a fuel system cleaner and took it on a good run and it did seem to help but didn't last. Now the lockdown restrictions have eased I'll be driving further again so if it is the short journeys hopefully it will sort itself out.
 
[/quote]
Possibly, if it never gets a long run?
But hey, a blast up the road from Diss to Attleborough should help that, and you'd go home with lots of new worries about codes you never knew you had. :poke: :D
We're considering a run to Southwold over the weekend. Don't suppose you'd fancy meet up there?
[/quote]

I only just saw this message, I wasn't ignoring the invite to Southwold 😂 if you've gone today it's a lovely day for it, my roof was down on the way home from work.
In normal times it would be driven on longer journeys more regularly but with lockdown the last few months mostly has just been my drive to work.
 
Possibly, if it never gets a long run?
But hey, a blast up the road from Diss to Attleborough should help that, and you'd go home with lots of new worries about codes you never knew you had. :poke: :D
We're considering a run to Southwold over the weekend. Don't suppose you'd fancy meet up there?
[/quote]

I only just saw this message, I wasn't ignoring the invite to Southwold 😂 if you've gone today it's a lovely day for it, my roof was down on the way home from work.
In normal times it would be driven on longer journeys more regularly but with lockdown the last few months mostly has just been my drive to work.
[/quote]
Cheers, we didn't go. Ended up pottering in the garden. Bet Southwold was packed anyway. Once things normalise, I reckon the Norfolk bunch may be getting together again for a run out. Failing that, a meet up and blast to the coast is always a welcome event.
 
An update after getting the code reader on it. No fault codes were stored that have anything to do with the issue (there were a couple of others)
We got some readings which mean nothing to me so no idea if normal or not. I will list them below so any help would be much appreciated.

Before cat reading of 2.0, after the cat 0.7
Oxygen sensor readings at idle - additional mixture 1: 0.2 Additional mixture 2: 0.55
At 2500 rpm 0.06 and 0.11
With the MAF disconnected readings were the same
Multiplicative mixture 1: -3.63 Mixture 2: -0.42

Cylinders true running value at idle
1: between -10 and -20
2: +25 to +35
3: -30 to -50
4: +15 to +30
5: +70 to +80
6: -70 to -90
 
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